Such a vane is known, for example, from U.S. Pat. No. 5,498,133 on which the invention is based. It has a vane blade with a suction side and a pressure side wall that are connected via a leading edge and a trailing edge with each other. The walls define the profile form and enclose a cavity used for cooling purposes. The cavity extends essentially radially, and a cooling medium, usually air, flows through it. The flow through the cavity may, for example, be direct. Alternatively, the cavity may be provided with an insert, whereby the air is usually supplied radially to the insert. The perforation in the insert then causes the air to pass between the insert and the suction or pressure side wall and to be guided to the trailing edge.
In the area of the trailing edge, cooling channels are provided that originate from the cavity and end in the form of blow-out openings in the area of the trailing edge. They extend through a vane section that adjoins the trailing edge and is formed by the corresponding sections of the suction side and pressure side wall together. This means that the cooling medium is able to flow from the cavity through the trailing edge area and cool it before exiting at the trailing edge and being mixed into the process gas stream.
Such a cooling concept also can be realized in gas turbine vanes which are manufactured--as is currently preferred--by using casting processes. The cooling channels are hereby created using a core that must be removed from the component, i.e., from the vane, after the casting. When designing cooling channels, it must be noted in this connection that the corresponding cores also must be producable at a reasonable cost. Usually two- or multi-part core form tools into which the core material is pressed in the molten state are used for this purpose. After solidification, the core tool is opened, and the core can be removed. Since the core consists of a number of side-by-side, connected individual cores, a geometry must be chosen for the overall structure that permits an easy removal from the core form tool. Of importance in this connection is the so-called taper angle that causes a side contour of the individual channels originating from the dividing plane and extending backward at an angle. As a result, the cooling channels in vanes of this type usually were located so as to be located centered between the suction side and the pressure side.
In particular in the case of vanes with a thick trailing edge, this concept causes the cooling channels to be relatively far removed from the two outside walls, so that the cooling effect is very limited.